add netbox role for ensuring netbox is deployed as specified

The role takes over the deployment of netbox and its dependencies, while
still requiring the user to provide the netbox version, db password and
config as well as to set up a web server and handle stuff like creating
users, etc.

roles/netbox/README.md

@@ -0,0 +1,77 @@
+# `netbox` role
+
+A role for setting up NetBox.  
+It automatically pulls in all required dependencies like Redis and PostgreSQL, deploys the provided systemd services and gunicorn config and sets up a PostgreSQL database named `netbox` with an owner named `netbox` and the specified password.
+However providing the [NetBox configuration](#netbox-configuration), [setting up a web server like nginx to proxy to gunicorn](#web-server-setup) and tasks like creating users, etc. you have to do yourself.
+
+## Supported Distributions
+
+Should work on Debian-based distributions.
+
+## Required Arguments
+
+- `netbox__version`: The NetBox version to deploy.
+- `netbox__db_password`: The password to use for connection to the database.
+  This is required since the upgrade script runs as root and therefore peer authentication doesn't work.
+- `netbox__config`: The NetBox config to deploy.
+  See [NetBox Configuration](#netbox-configuration) for more infos.
+
+## Optional Arguments
+
+None.
+
+## NetBox Configuration
+
+The NetBox configuration should include a connection to Redis as well as a connection to PostgreSQL.  
+Configuration for the Redis connection:
+
+```python
+REDIS = {
+    "tasks": {
+      "HOST": "localhost",
+      "PORT": 6379,
+      "USERNAME": "",
+      "PASSWORD": "",
+      "DATABASE": 0,
+      "SSL": False,
+    },
+    "caching": {
+      "HOST": "localhost",
+      "PORT": 6379,
+      "USERNAME": "",
+      "PASSWORD": "",
+      "DATABASE": 1,
+      "SSL": False,
+    },
+}
+```
+
+Configuration for the PostgreSQL connection:
+
+```python
+DATABASE = {
+  "HOST": "localhost",
+  "NAME": "netbox",
+  "USER": "netbox",
+  "PASSWORD": "<same as netbox__db_password>",
+}
+```
+
+Further configuration should take place. Some relevant resources can be found here:
+
+- Installation guide configuration docs: <https://netboxlabs.com/docs/netbox/en/stable/installation/3-netbox/#configuration>
+- Configuration docs: <https://netboxlabs.com/docs/netbox/en/stable/configuration/>
+- Example configuration: <https://github.com/netbox-community/netbox/blob/main/netbox/netbox/configuration_example.py>
+
+## Web Server Setup
+
+As this role just sets up gunicorn, but doesn't set up a web server, you need to do that yourself.  
+The relevant documentation on how to do that can be found here:
+
+- Web server setup docs: <https://netboxlabs.com/docs/netbox/en/stable/installation/5-http-server/>
+- Example base nginx config: <https://github.com/netbox-community/netbox/blob/main/contrib/nginx.conf>
+
+## Links & Resources
+
+- The NetBox Git Repo: <https://github.com/netbox-community/netbox>
+- The NetBox installation docs: <https://netboxlabs.com/docs/netbox/en/stable/installation/>